The abnormal relationship between upper and lower dental arches can be manifested as mandibular protrusion, mesial malocclusion and anterior crossbite. It is mostly caused by poor breastfeeding posture, retention or premature loss of anterior teeth of deciduous teeth, congenital absence of upper permanent incisors, bad living habits, insufficient abrasion of canine teeth of deciduous teeth, systemic diseases and hereditary mandibular protrusion. According to different degrees, it can be manifested as anterior crossbite and neutral molar occlusion. In severe cases, anterior crossbite, posterior mesial occlusion and mandibular protrusion coexist.
Etiology and pathology
1. Bad oral habits
(1) Bad breast-feeding posture, such as improper bottle feeding, requires the jaw to suck forward forcefully, which may cause anterior teeth to be reversed.
(2) The bad habit of biting the upper lip or mandibular protrusion can lead to anterior crossbite and mandibular protrusion.
2. Local obstacles in dentition replacement
(1) Retention or premature shedding of deciduous teeth may cause individual anterior crossbite.
(2) Early loss of maxillary deciduous molars and backward movement of maxillary permanent anterior teeth can form anterior crossbite.
(3) deciduous underwear and prostheses with mandibular protrusion higher than dental arch.
(4) Congenital absence of upper permanent incisors, such as common maxillary lateral incisors, can lead to hypoplasia of the anterior maxilla and form anterior crossbite.
3. Disease
(1) Chronic inflammation of palatal tonsil or lingual tonsil stimulates mandibular protrusion, which may lead to anterior teeth inversion and mandibular protrusion over time.
(2) Patients with cleft lip and palate often suffer from maxillary hypoplasia, which easily leads to anterior crossbite and mandibular protrusion.
(3) Patients with rickets have disordered calcium and phosphorus metabolism and abnormal facial muscle dynamics, which often lead to severe mandibular protrusion or anterior teeth opening deformity.
(4) Endocrine diseases, such as hyperfunction of anterior pituitary, can cause mandibular protrusion deformity.
4. Hereditary pre-abuse with mandibular protrusion has obvious family background, and the mandible and face are abnormal.
clinical picture
Anterior crossbite, the face can be characterized by mandibular protrusion and maxillary hypoplasia.
Diagnosis and differentiation
The abnormal relationship between upper and lower dental arches can be manifested as mandibular protrusion, mesial malocclusion and anterior crossbite. It is mostly caused by poor breastfeeding posture, retention or premature loss of anterior teeth of deciduous teeth, congenital absence of upper permanent incisors, bad living habits, insufficient abrasion of canine teeth of deciduous teeth, systemic diseases and hereditary mandibular protrusion. According to different degrees, it can be manifested as anterior crossbite and neutral molar occlusion. In severe cases, anterior crossbite, posterior mesial occlusion and mandibular protrusion coexist.
1. Bad oral habits
(1) Bad breast-feeding posture, such as improper bottle feeding, requires the jaw to suck forward forcefully, which may cause anterior teeth to be reversed.
(2) The bad habit of biting the upper lip or mandibular protrusion can lead to anterior crossbite and mandibular protrusion.
2. Local obstacles in dentition replacement
(1) Retention or premature shedding of deciduous teeth may cause individual anterior crossbite.
(2) Early loss of maxillary deciduous molars and backward movement of maxillary permanent anterior teeth can form anterior crossbite.
(3) deciduous underwear and prostheses with mandibular protrusion higher than dental arch.
(4) Congenital absence of upper permanent incisors, such as common maxillary lateral incisors, can lead to hypoplasia of the anterior maxilla and form anterior crossbite.
3. Disease
(1) Chronic inflammation of palatal tonsil or lingual tonsil stimulates mandibular protrusion, which may lead to anterior teeth inversion and mandibular protrusion over time.
(2) Patients with cleft lip and palate often suffer from maxillary hypoplasia, which easily leads to anterior crossbite and mandibular protrusion.
(3) Patients with rickets have disordered calcium and phosphorus metabolism and abnormal facial muscle dynamics, which often lead to severe mandibular protrusion or anterior teeth opening deformity.
(4) Endocrine diseases, such as hyperfunction of anterior pituitary, can cause mandibular protrusion deformity.
4. Hereditary pre-abuse with mandibular protrusion has obvious family background, and the mandible and face are abnormal.
Anterior crossbite, the face can be characterized by mandibular protrusion and maxillary hypoplasia.
1. Tooth development is mostly caused by local obstacles in the process of tooth eruption or replacement, often showing simple anterior crossbite. The reverse coverage is small, and the molar is neutral or close to neutral. The shape and size of mandible are basically normal, there is no obvious abnormality in jaw, chin is not prominent, and face is basically normal. The mandible can retreat to the front teeth by itself. X-ray cephalometry has no abnormal morphological structure, easy correction and good prognosis.
2. Osteogenesis is mostly caused by genetic and disease factors, except anterior crossbite, accompanied by jaw deformity. It can be manifested as blunt mandibular angle, long mandible, short mandibular branch or underdeveloped anterior maxilla. The chin is obviously protruding forward, and the lower jaw often cannot retreat on its own. The face is depressed, sometimes accompanied by jaw opening deformity. It is difficult to correct, and the effect of simple orthodontic treatment may not be good.
This mechanism of anterior teeth back pressing can be divided into three types:
(1) The anterior maxilla is undeveloped and the mandible is normal.
(2) The maxilla is normal and the mandible is overdeveloped.
(3) Maxillary hypoplasia with overdevelopment of mandible.
3. Functionality Due to poor breastfeeding posture, functional overstretching of mandible leads to mandibular protrusion and anterior teeth locking. Some people call it sexual mandibular protrusion. If it is not corrected early, it may develop into a real mandibular protrusion over time.
4.x-ray cephalometry
The (1)SNB angle and facial angle increase, indicating that the mandibular angle increases relative to the skull base protrusion. The above measurements are normal in patients with odontogenic anterior crossbite.
(2) When mandibular protrusion is accompanied by maxillary retraction, the SNB angle decreases according to S-PTM and PTM-6. The above measurements were normal in patients without maxillary recession.
(3) (3) The ANB angle and AB plane angle increase, and the AO-BO value decreases, indicating that the maxillary and mandibular joints are obviously not adjusted, and the above-mentioned measured values of odontogenic anterior crossbite are basically normal.
(4) The protrusion angle (G-Sn-Pg ") increases and the H angle (H line -N"P"g) decreases. The increase of Z angle (FH-H line) indicates that the scoliosis of soft tissue decreases. The protrusion of the upper lip (Ls-SnPg ") is decreased or normal. The protrusion of lower lip is increased. The maxillary protrusion distance (Sn-G) decreased or was normal, while the mandibular protrusion distance (PG "-G) increased.
treat cordially
The abnormal relationship between upper and lower dental arches can be manifested as mandibular protrusion, mesial malocclusion and anterior crossbite. It is mostly caused by poor breastfeeding posture, retention or premature loss of anterior teeth of deciduous teeth, congenital absence of upper permanent incisors, bad living habits, insufficient abrasion of canine teeth of deciduous teeth, systemic diseases and hereditary mandibular protrusion. According to different degrees, it can be manifested as anterior crossbite and neutral molar occlusion. In severe cases, anterior crossbite, posterior mesial occlusion and mandibular protrusion coexist.
1. Bad oral habits
(1) Bad breast-feeding posture, such as improper bottle feeding, requires the jaw to suck forward forcefully, which may cause anterior teeth to be reversed.
(2) The bad habit of biting the upper lip or mandibular protrusion can lead to anterior crossbite and mandibular protrusion.
2. Local obstacles in dentition replacement
(1) Retention or premature shedding of deciduous teeth may cause individual anterior crossbite.
(2) Early loss of maxillary deciduous molars and backward movement of maxillary permanent anterior teeth can form anterior crossbite.
(3) deciduous underwear and prostheses with mandibular protrusion higher than dental arch.
(4) Congenital absence of upper permanent incisors, such as common maxillary lateral incisors, can lead to hypoplasia of the anterior maxilla and form anterior crossbite.
3. Disease
(1) Chronic inflammation of palatal tonsil or lingual tonsil stimulates mandibular protrusion, which may lead to anterior teeth inversion and mandibular protrusion over time.
(2) Patients with cleft lip and palate often suffer from maxillary hypoplasia, which easily leads to anterior crossbite and mandibular protrusion.
(3) Patients with rickets have disordered calcium and phosphorus metabolism and abnormal facial muscle dynamics, which often lead to severe mandibular protrusion or anterior teeth opening deformity.
(4) Endocrine diseases, such as hyperfunction of anterior pituitary, can cause mandibular protrusion deformity.
4. Hereditary pre-abuse with mandibular protrusion has obvious family background, and the mandible and face are abnormal.
Anterior crossbite, the face can be characterized by mandibular protrusion and maxillary hypoplasia.
1. Tooth development is mostly caused by local obstacles in the process of tooth eruption or replacement, often showing simple anterior crossbite. The reverse coverage is small, and the molar is neutral or close to neutral. The shape and size of mandible are basically normal, there is no obvious abnormality in jaw, chin is not prominent, and face is basically normal. The mandible can retreat to the front teeth by itself. X-ray cephalometry has no abnormal morphological structure, easy correction and good prognosis.
2. Osteogenesis is mostly caused by genetic and disease factors, except anterior crossbite, accompanied by jaw deformity. It can be manifested as blunt mandibular angle, long mandible, short mandibular branch or underdeveloped anterior maxilla. The chin is obviously protruding forward, and the lower jaw often cannot retreat on its own. The face is depressed, sometimes accompanied by jaw opening deformity. It is difficult to correct, and the effect of simple orthodontic treatment may not be good.
This mechanism of anterior teeth back pressing can be divided into three types:
(1) The anterior maxilla is undeveloped and the mandible is normal.
(2) The maxilla is normal and the mandible is overdeveloped.
(3) Maxillary hypoplasia with overdevelopment of mandible.
3. Functionality Due to poor breastfeeding posture, functional overstretching of mandible leads to mandibular protrusion and anterior teeth locking. Some people call it pseudomandibular protrusion. If it is not corrected early, it may develop into a real mandibular protrusion over time.
4.x-ray cephalometry
The (1)SNB angle and facial angle increase, indicating that the mandibular angle increases relative to the skull base protrusion. The above measurements are normal in patients with odontogenic anterior crossbite.
(2) When mandibular protrusion is accompanied by maxillary retraction, the SNB angle decreases according to S-PTM and PTM-6. The above measurements were normal in patients without maxillary recession.
(3) (3) The ANB angle and AB plane angle increase, and the AO-BO value decreases, indicating that the maxillary and mandibular joints are obviously not adjusted, and the above-mentioned measured values of odontogenic anterior crossbite are basically normal.
(4) The protrusion angle (G-Sn-Pg ") increases and the H angle (H line -N"P"g) decreases. The increase of Z angle (FH-H line) indicates that the scoliosis of soft tissue decreases. The protrusion of the upper lip (Ls-SnPg ") is decreased or normal. The protrusion of lower lip is increased. The maxillary protrusion distance (Sn-G) decreased or was normal, while the mandibular protrusion distance (PG "-G) increased.
1. headgear and traction chin pocket correction device. Tongue-spring appliance suitable for the back pad of early skeletal anterior teeth can be used in combination.
2. Front traction correction device. It is suitable for early skeletal anterior crossbite with maxillary hypoplasia and mandibular protrusion, and can be used for dentition replacement or early permanent teeth.
3. functional orthosis, such as activator or Frankelⅲⅲ. It is suitable for early skeletal anterior crossbite and can be used in dentition replacement period, especially in the late dentition replacement period.
4. Class 4.III traction correction device. It is mainly used to adjust the mesiomandibular relationship, and is often used as an appliance for the back pad of early skeletal anterior teeth, or a fixed appliance, or both.
5. The removable maxillary appliance can be used alone, or combined with other plastic devices (such as mandibular pocket) and appliances (such as fixators). See Chapter 7 for specific equipment and applications.
6. Fixed appliances include edgewise edgewise edgewise appliance and Begg appliance, which can be used to correct anterior crossbite and are often used in mixed or permanent dentition. When using Begg appliance, the traction force should be about 80g.
7. Adult anterior crossbite needs orthodontic and surgical orthodontic treatment.
Prognostic prevention
The abnormal relationship between upper and lower dental arches can be manifested as mandibular protrusion, mesial malocclusion and anterior crossbite. It is mostly caused by poor breastfeeding posture, retention or premature loss of anterior teeth of deciduous teeth, congenital absence of upper permanent incisors, bad living habits, insufficient abrasion of canine teeth of deciduous teeth, systemic diseases and hereditary mandibular protrusion. According to different degrees, it can be manifested as anterior crossbite and neutral molar occlusion. In severe cases, anterior crossbite, posterior mesial occlusion and mandibular protrusion coexist.